November 30, 2010
English, Hebrew and the brain’s language-reading process
Is the English-reading brain somehow different from the Hebrew-reading brain? You might not expect any major differences; after all, both languages are alphabetic and are read more or less phonetically by breaking words into their constituent sounds. Compare English and Hebrew to a logographic language like Chinese or Japanese, and the similarity between the alphabetic languages becomes obvious. But new research by Hadassah University researchers Atira Bick and colleagues, published online in October in the Journal of Cognitive Neuroscience, found that despite their similarities, there are some key differences in the way the brain processes English and Hebrew words.
What it comes down to is the way words are constructed. In English, prefixes and suffixes are added sequentially to meaningful base words (for example, “dark” in “darkness” or “darker”), whereas most Hebrew words are built up from three-letter roots (for example, “rikud,” a dance, and “rakadti,” I danced, from r.k.d). As a result, in the process of determining the meaning of a word, Hebrew readers search for the word’s root, while English readers focus on separating out the individual letter strings within a word. This allows Hebrew readers to classify words on the basis of morphology, or word structure, while English readers tend to classify words on the basis of semantics, or meaning.
Given this subtle distinction in the method by which English and Hebrew readers process words, the researchers wondered: Do Hebrew-English bilinguals use a common network in the brain for word processing? And, if both languages do recruit a common set of neural structures, are there differences in the way those structures are used? In order to address these questions, the researchers recruited 27 bilingual adults, all of whom were highly proficient in both languages, to participate in an MRI experiment. Participants were shown word pairs in both languages which were either similar in meaning only (like “demand” and “ask”), in morphology only (“department” and “depart”), or in both meaning and morphology (“guilty” and “guilt”).
They found that although both languages activated the same parts of the brain, the activation itself differed on the basis of morphology. In Hebrew, morphological processing was unaffected by the meaning of the words: Hebrew brains would similarly process word pairs that were similar in morphology, irrespective of any differences in meaning. This means that “hachlama” (recovery) and “chalam” (dream) would be treated no differently from “gishur” (bridging) and “gesher” (bridge), even though the first word pair is unrelated in meaning while the second word pair is semantically related.
It’s a different story for English though. In English, morphological processing differed according to whether words had shared meaning: “darker” and “dark” resulted in the same brain activation patterns, while “corner” and “corn” did not.
At first glance, this might not seem like such a big deal. But the implications of this research bear on one of the most basic questions of science: How does experience shape biology? All of the participants in this experiment were Hebrew-English bilinguals who were exposed to both languages early in life and had demonstrated proficiency in both languages at the time of their participation. That the same brains processed the two languages differently suggests that the organization of the neural circuitry for reading depends on the particular features of the language being learned, rather than on some common mechanism being applied to all languages in exactly the same way. Biology offers the basic blueprint in the form of shared neural circuitry, while linguistic structure determines the way in which the brain processes that particular written language.
More research is necessary, but at least one thing is certain: neither nature nor nurture alone governs the process of learning how to read. Instead, they operate in tandem, resulting in a far more flexible system than either might produce alone. And if you’re trying to learn Hebrew, focusing on learning the three-letter roots couldn’t hurt.
Jason G. Goldman is a graduate student in developmental psychology at USC. Find his science blog online at jasonggoldman.com or on twitter: @jgold85.